This invention relates to a packaging material for a photographic photosensitive material which improves photographic properties with keeping good dimensional stability, physical strength, moldability and so on.
Packaging materials for photographic photosensitive material are required to have good properties about dimensional stability, physical strength, moldability and so on, as well as not to affect photographic properties adversely.
For example, a packaging film disclosed in Japanese Patent KOKOKU 2-2700 comprises a light-shielding film containing 50 wt. % or more of L-LDPE resin and 1 wt % or more of a light-shielding material.
A molded article for a photographic photosensitive material disclosed in Japanese Patent KOKAI 7-237958 is made of a resin composition comprising 50 to 99.98 wt. % of thermoplastic resin having a small molecular weight distribution of 1.1 to 10.0 and a MFR of 0.1 to 100 g/ 10 minutes and 0.01 to 15 wt. % of lubricant for the improvement in moldability, and improved in dimensional stability, moldability, lubricating properties, etc.
A thermoplastic resin packaging material for a photographic photosensitive material disclosed in Japanese Patent KOKAl 8-179473 improves photographic properties by descending melting point by using a polymer material having a low molecular weight polymer content of 3 wt. % or less manufactured using a metallocene catalyst.
However, in the above packaging materials for a photographic photosensitive material, in order to remove adverse effects upon photographic properties entirely, resin used becomes expensive. Moreover, rust generates upon using a molding machine or a mold which contains iron.
Furthermore, in the case of the packaging film disclosed in Japanese Patent KOKOKU 2-2700, film moldability of thick film having a thickness of 50 .mu.m or more is inferior due to great melt viscosity, although the film is very excellent in physical strength, which can make the film thinner, and in heat sealing properties.
The thermoplastic resin packaging material for a is photographic photosensitive material disclosed in Japanese Patent KOKAI 8-179473 is also inferior in film moldability, such as the occurrence of melt fracture, due to great melt viscosity compared with the L-LDPE; resin having the same MFR and density manufactured using a conventional Ziegler catalyst, although the resin has a narrow molecular weight distribution, excellent physical strength and excellent antiblocking ability.